Add percent/count toggle to stack bar chart, other small design changes

[jeremiak]

Closes 18F/crime-data-explorer#198

[brendansudol]

can you post screenshots of how this now looks here (as well as how this looks on mid/small screens when this nibrs card is stretched)?

[jeremiak]

Here is how this looks across a few different display sizes:

The most problematic to me is this stretched breakpoint, but not sure if this is problematic. I do think this might look better with the bar chart centered as it was. Perhaps we center the chart but keep the rest of this in place?

[brendansudol]

i agree with you @jeremiak that this looks better when centered (with the bottom axis to keep it from just floating and making it consistent with the histogram chart below)

When left-aligned, I feel like there's too much white space in the middle; having content on the edges but not the middle seems less than ideal.

I would be in favor of keeping it as is (vs. how it looks in images above) -- curious for @AvivaOskow and @LarryBafundo to offer their thoughts here

[jeremiak]

Thanks for the feedback @brendansudol. I'm going to remove 946a4ed but merge the rest